Cornerbeads are the metals that protect and define corners in your spaces when working with drywall. In remodeling as well as new work, intersections where beads meet, can be tough to blend. Case in point is the Guest Bath Towel Storage opening.
Opening
Here is the raw opening for the towel shelf. Because the wall already has an existing texture and the back side of the opening is rough, I will use 5/8” ‘J’ bead to frame in this opening.

Bead
Here is the opening with the bead in place. It looks smooth, but the corners are not perfectly flat in relationship to each other. Because there is no backing behind this opening, I elected to glue the beads in place with PowerGrab, the best construction adhesive ever.

Prefill
To eliminate the elevation difference problem, I prefill the corners with mud, at a 45 degree angle to the corner.
Note: Here is where 5 minute speed set shines.
Starting from the inside of the opening and mudding onto the wall, I now have a smooth corner for the next coats. What is not shown in the photo is the mud that gets trapped on the bead inside the corner that you must remove.

Fill Coat
Here is our opening with the tape and mud in place. Using USG Dust Control mud, our new best friend in remodeling. I now have a flat face and a smooth inside corner without any ridges that would make this look bad. I am a bit anal about this because regardless how straight your walls are, how well you taped, having twisted, ridged, beads looks bad.

Here is our opening with the texture applied prior to painting. It will look great.

You can do this yourself. A little time and care, your house will look like a million bucks.
I’ve been seeing a trend in new construction that they are using rounded corner bead now. Personally, I can’t stand the stuff. But hey, I like old houses so I got nothing to worry about. Anybody using the rounded cornerbead in a remodel should inexcusably have their renovator card revoked.
It awesome to stumble on a bit of extra information when renovating and designing (or planning too). If you are looking for a few expert tips, I also highly recommend checking Masterrenovator.com, the guy has very good info for things that can keep you out of trouble.